SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be2f7db933101416626ae412d2815717907679ec1ad88f005823f40c6c6252c1' 
  AND token = 'mdXvxmRXujC26TsGuhSNXuZcYn8DLcDtkxABSve0Mw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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