SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b7751867abe7eec784cda254b8452037a1c0ecc99eb9295ee564f32af2384a0' 
  AND token = '420dapZP/YP1MCoS/T0elkNvXk3Y9nhXD9/ITIQpeNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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