SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a359db62f2cf2b2a584ebb9758cd884251aec780080ec67a3fc993716db5f072' 
  AND token = 'LUu8V5/8swQaOCFrJubel7mOGtCDMqFxE/NtiPZeRl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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