SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c84b67055ef5fa79b3e32177e7bc4768d1149620e1bdd489a35f3418a31832a4' 
  AND token = 'P85lXrrj+V4wxWhuBL/37ai9JAbq683YZPUc6InGrcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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