SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7582cb9f73f270edb9f71028b71f35e5168b0a2178d875f7c8c8f95bc946655' 
  AND token = 'cVxCb2hUfDfi6CpEzpxkXbRPjvdFRNAt7vsqv5DxdJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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