SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b9cde2d6a9dffa3661d8294ad3007aee9c595416d7b99d455f492f51734e15' 
  AND token = 'n+jql/fYhnWqlEtreFNeHanWOazerhq3K6eooXMbloQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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