SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d06ff9e1e25829bd1b74c8f7f6c41435f784d31726f3df1952b446bf8346be' 
  AND token = 'vKZOvnzuDR+vsfKVLXK5NsC68v7ksHE3CDZhaY3VSfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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