SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '540993e2758c2fde9d0950ce77561afe209d229a627ed74989daf433d1f15981' 
  AND token = 'M/3TAjnKaccwXPGkMWLyUXXUgGTFnlY6aR04oyQk97I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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