SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835061020c457d988b77ae7a63b4b7a50bb42741c63b41f568f8ccf8a609aff1' 
  AND token = '0BOgqiVQVQhZyHKF/3xcsc++ubedy2RV1ZwmtSPTP4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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