SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9470c2c76b4af87f3cf306088d33e3a8ae48a766a049656ae77d7673873ad75' 
  AND token = 'z2BqT9vgSMwtpKY2huH0RwPwtXPwY1WFTzJbHuj9hkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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