SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f50b02664bd32ce3160b11ec154a05bb454d92f7574475354a643b58bedbc8' 
  AND token = 'YTsuG467FIAwhetDF93l2ifTbUzoo187Pl9T6L50xIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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