SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e4e294b6fbaccf61b377bf672594133d36600191040b1b30b29add7685761ed' 
  AND token = 'TOb/6ysYXt+PcvvUPdaC1L6C3B6KVJH5OmmdDbDXGoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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