SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6259e1d9d3887af06a39057eefb4b198992361cc60d05c250d550c1e23fa326f' 
  AND token = 'StJPPf3dQqAVvAlEX4Sus/vuup8Men16c5DeY1TrbnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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