SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6283f6bc81546a8efbc9a1f21e64e19c7bc7e6829102601043dfce16fab9144a' 
  AND token = 'LBj5I39PAcJ/NFOC3fnwnHBLUAN3mRCmZpVzleoazC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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