SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4cdfb370112443f85f3928663e21ccb22f37150350e15331db9fb329f41f92b' 
  AND token = 'L5vhKqYA0id7LOCBmlpeThahUb8gVC/2zfLcMMSSVwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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