SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8a3924700c1f4eb15512280c8b2524c160492794b0d36abcc42ff72d8e06584' 
  AND token = 'jZUd7NBzxLEM0xmMIOaoyoOpDVLfSCjCVkAdvpQl6L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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