SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5f063acabcc21932e81b2e2121e7a892a8703b0ff5b393a29601ba941ef87b6' 
  AND token = 'kkln6qySAc8b+YzPb5vHGGW6VSmjYvt3gDHyXeIsIPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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