SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e997821956590e52389fd0f1c06a3a53a45f96c5583bdcc91e202700da9940' 
  AND token = 's3dWsEYgVm7zW/faERrhLIYfIaocJW7acdY3XW4YcfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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