SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e38e7a4a921a09c57af349affd3c95b16c77fd3b8051d5cb982342aa0461bd40' 
  AND token = 'U65QguuQpXI76CNnM7++qIRR8rvE7hu8OvwwYLXUT6w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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