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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c748a703460b1c6171ad8e636f6e493e4bfd91c6c8e86e2cde89d2a009045b4c' 
  AND token = 'wXjRzp0RPUtCrMOa2bbMcgiKpuhdKHl88VyK5XgPEjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}