SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ffc88a9c54fcb17aff32116b9c05ad80568861da452f66d1d2fa8e62ebc68da' 
  AND token = 'qvfSZmQ9r8ADvYrilWXB1GIc9nOf7pohJRpVuc/tnoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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