SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5c164a593993e25dd7dbd8e4269ecf3dfe30d9a78b9f0566d9f858f25c0fae3' 
  AND token = 'iEVisyFwp6wEQGT+R29mmVVaLWQS18AG4Yiqa6VOsHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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