SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83b415105801b90e89a2bedbd58291cc483c6716fe94464c5530d24e37679ed6' 
  AND token = 'y+reRORw13EdUg+bZdPFr0PS8c1SpLB7/dwRAevXFnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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