SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0389f60875fb98924deaad7472dce1f1051555a1032f1ef519b1b5ac73e98794' 
  AND token = 'JN43qo7TrAAmwh35lDEKwrmPdjPdVzRIl7CsOa54yDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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