SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '942b793284451e8fe51e79f37cafa96fb5fcb847c12d51d5d36634017eea4b55' 
  AND token = '0nUGcCcwY+SrxD5j6VQ+6lPvGeJTsMKoayUBl8cvJbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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