SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3115727f04c89af421bd19fd957ec2155b00009edefe28b71f2fb1488bf0fa33' 
  AND token = 'eKGCm9wE+IES2Wt3P2K9PH0Kjvs+Q99EDtyajsMGa2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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