SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f35431de099f06cd773eb428fcd5450e1d1b139500b3803e856825ca7c210c3' 
  AND token = 'sVbiTx2TcCWEIVs9zcC+sBv43hWVdhpaZe4125AAnOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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