SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '338a65b2c09d41df53dc9134687bb0513285d5798717b7fd2ec7660127eac585' 
  AND token = '52vDyHgZiwFSIDuw6dC3GSN2SAoLzatTXPz2i0Mt/yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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