SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dd232c1f1bb7499698533882d5a5b70556ee6395976f1ce82a51c7134f1f43d' 
  AND token = 'TZJRZJOnfFebV9wH80w4kuh+ziu1jgDUxlGWhR53fIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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