SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c8cf7d88e9d0b7c4cf0fd8a8f47e4a46719e256c4e5cec63234af3308343bf3c' 
  AND token = 'WrbbEhF9qXhRvANb1UGw/UsVNJauWMY5NVNX+1ORMDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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