SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4ff7adfa35990ee1008d92fe8f43067257ef59ee783d9c449ebb58f3f09df30' 
  AND token = 'R/pFnr+DIVDoGMlTKPBm6fUjD2qYp3j7XlV+Lp8aM+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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