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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f8ef6dd4e8f7e1655269059efd7fc8ffd6c435f9f98d9e1d6c967517af11d87' 
  AND token = 'DWHT0HZe/lQFHvD4TxzYwKScrUvpmafCdF3O1/2ffAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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