SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '677f0d8bcf607c2d622e68fbf6fabec90b2ab76cd29ba2491b841f44a503213d' 
  AND token = 'EvGrjyPLv+bwKOhkUQczCbdGpS/pKLmQNKS/Rpwm6uQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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