SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4919a0f43cd0fdcf345196a7852b1bae45014efd28e325a10d2016966582ff9' 
  AND token = 'LTPDxXsNWeZEalNk6jXsIW4JWjKxGz/3yJFShP4sKbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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