SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dc9279488ee86db6081f14f7d1ab2a5afeb59cc5d44b8452225388dbb4a9d7c' 
  AND token = '2+71thKokCpD+mluyOqmGQKWL/UGN207iXzVF+zxkcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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