SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39ebe9e19068679d91fd86a0e2618f62658c6a8e0c7b8b07bcd1fcebd1af2d18' 
  AND token = 'Yp32AHnmiFOcuFVFax2tX8Glnc8qmvtIcyYIHdsMMYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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