SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d0ad4eaf9ae2f8fb7ee278fa25734f679f531d6698ec49e20a52792b3640121' 
  AND token = 'qWLdKGPmmYKGZYaQFQJi/cNBLxkVlY4tdsQQWmCuF28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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