SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a542696cf05b39fe225d8a8f4d1940970b3bd1645c48378cc63c23ef2776045e' 
  AND token = 'Nj5VCn6IHvNRY/oKSTUOxbGEppUrHSg/Pjh7hBm6Znk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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