SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '356f79a65d1daddb2cdbc194c935a2e228740baab1b0fd87f616febd519ebcd7' 
  AND token = 'j+xvW2RagPzm/L/OsDteVcGFTfRWF5HRPjqG7ZK4UYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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