SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad7f38622eb4ac0c291718824aa23cde935f44a3599c2a04ecd9b355eef304a' 
  AND token = 'RNfGdsWbljIhCsQOtvNiaUfnsXHz9oc4g2JJRaD9nV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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