SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef0df68b0253af4e8fffb799c2fdb19fa7bfafdfe48e93617c1f778d0d2a4f13' 
  AND token = 'QWa8sUA8eYCVuH8fP1fLpP+sVmkQssFNto1ZODsyA+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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