SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8029fa50f36c50be817d4a1eb7fcc0e0292517a884c2a93ed91066df04e9c94' 
  AND token = 'sjBSvncjwj+bnWCKVPNIqA+Zr4YROdqW5QILFfh7C04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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