SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '846cf638ba423ba0e60571e86e3463db30a1cf7b5a6a29d0387f1b322b099a28' 
  AND token = 'L+Oo/FzBMS2gl6Wx0OOioAOwyYwjeZSM0JJG6hpZ6mY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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