SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6609e1e6f1250b12220cba09088849689f946880eecbbef21b18f9e43fd4f992' 
  AND token = 'iCphJ18892T16RBZH8ISRwLIeFuFveGmNOJ53LmzcVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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