SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8330efd8b76dfb7601fb60a139c639d5a6e6928c2b4b67ccc9a30f32b7255794' 
  AND token = 'DI2XlnkMj5hGyVavwW3fIUKtuDJ9FyFUFgC44uPiXfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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