SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff50dc74b209de9f5322ca5b8553d9631582d5bd864631e159fef2e2fd15d698' 
  AND token = 'zUTO92a39NUAj8SlbQuTEnpMq0DWlAlpUUOdQZfmKHE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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