SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c973ef33602f0761a3cd3cc844b84ece81a4581e69666b5703abce1f128574d4' 
  AND token = 'gTqwe5+OMPTUKnkhovDRUD+1jUqix0OQ9WLSCzYme/M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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