SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '91ad11c4206f5ac97c7fc291bca1ae0b47a0504db60ba17ca5de96b3a233ae8a' 
  AND token = 'zsEr/gMdeUzTAZDY6mhtTSArZMNHWkcoits/Jj8iDkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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