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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '748c3cd7d35efbe6ff9b0aeda781c071c152f3df33d05553e0abec5fee10fb33' 
  AND token = 'U6pYc0C7Gj5BxPtL8sFlKdpPVt78zWMh23x/UkY80MQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}