SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bb73827942394286998de1559120a76fe08722b58bf36c73695248eadcc9df9' 
  AND token = '53SdJlRSy5mKg9PLqnuNZ0RgeH+ob9DLu7IDNNTWERU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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