SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3b7f4b7c98ffc9aac7e5582cca86dd4eb945e976388f81c2088555e239baee0' 
  AND token = 'S1ux2ZxSGy8iwofcHm2fodfJR+oHzurd/awId0IouHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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