SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97a8a3e5fcf26b8d3904a6a86d7ba01d16a78323c3e8cafdf24bc89da6ed0927' 
  AND token = '5Bzwf1aMIfLT23YqYISMZhjZdVz/gtV6jrPJ/hIAUK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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