SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3401e25446ce607dc42bbecc314eb50da46262d5e3bd9c850d0524a9df406bd' 
  AND token = 'uRmETSrz8mN2hJMiUesNW83XxdyHwZQ9UA+BD4qaPyM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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