SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd52f0835ba494601811698696c16ef3410f2c8db62e81c188e83438e02b9fb5a' 
  AND token = 'Hd35ndm/FvuBmZHB1BmeRKapFDbAWsIyuuklHdH9uoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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