SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a34e9d1f099fad80b041f2f66595952de2f13026023fed483fd4985568558fdb' 
  AND token = 'lEgS8t/pGGYRrvDa2s29A0anGQsqKW+K1L5bDsh/HIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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