SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2bf880e5aedd79d59e3cdf12abe43572ecccc77ea43033bdda868623008cbc2' 
  AND token = 'N3r2k8z+msbOfrIephtPTUkkoD/WLkdnw/dap9jcOZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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