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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '897778f7ea3b471a56fea9df235e368531c5fa72bb44713b4bc22eb9abf2d8e7' 
  AND token = '6iJM6bIFs/VJ30rRP1e4fhoccY8mw60CYtHS2QRe+Vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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