SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56796ea8295f3a58694a0add24cfd420b5e2ee5ebb14320a15e81b6866985635' 
  AND token = 'W97I4gdXDhnWxirtXlFLbz3yykwgF9NlX25MryOlI6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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