SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '994a103834657e885be7a13072f49f854aa896dab38269ced041686d507cfe5e' 
  AND token = 'Qwt3mEituAXQ2HCud/qS0QtAzSXyyxiXVzUFuemcLP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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