SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f874ea9a08415ee88dbac2823733cca33736575d72ba0bce5a09e2ac34383ec' 
  AND token = '4mt8UfIONwqLXRihEKUIq0nD/Jbrg+lhWIw8EnVGAkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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