SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86f4ff2d66738410c11a9a2f449d08b245fa182c3b02f23511aa14183ddb1a41' 
  AND token = '8589buq1UhiBnbXabkIldpYwxMFftKKFtj7c7vWVSUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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