SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1948e0b98fa69654931abad56ba5b4202bf4858850278a67c3a7bf8692de8256' 
  AND token = 'DBd+eR/ZfcnsfPRAItsqLHJ5/RmBZCIxWqIeqoJ0vQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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