SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '535567822a95fc1ce98bdb6f1b788fc841af5878f130586b4c073d86c16a6d4f' 
  AND token = 'GrGaBohd8RXds7Bngo6dbgdjE+hjRCyDiQZHxPwgYxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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