SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dc10b0a87061b289b8be2ced5b2d7f4dce6d0c6253fd62952b94cae77aa715a' 
  AND token = 'mls/5gXvwwhge+dUF/WOERpqQE5rHiAU9uBe8ow6slI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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