SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '500c7f39485c5a6e22879aeb2c86adc0045b4d916748be49efba8b070d8b9f77' 
  AND token = 'dQj1ka8TcTCLxpaKiOFdgHRHjrtU2MfaWC91bqNbPAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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