SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '407dff81d789e9793eda7f7ea26c24e9035afec4fd6c0fa88f133a19980f1a00' 
  AND token = '8OnGQoiEzLA1f9pOjfUdkmqH/Nmuje/NoCoW3OwnHbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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