SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '392eeb656cf616f2bb7319a9b10271db2cd45094d208e23827c186943ea4adc5' 
  AND token = 'PwM/zwCWZbapJDAygKxAZWKVRZ36dxa8AnwKsUq8XNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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