SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac55f9f9ee2a59c5dbb54496a4aafd8820d12f95d138563b744c4d5664184e2b' 
  AND token = 'xLJOLmgb/JfV+QH30+Fn0ynuqGgrw7g1ZNR/2EzwJf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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