SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '993758500549ff46a16bcadf01d425f34c091cefc0575ad2ea29c98a6a28abe9' 
  AND token = 'uiAJwCSgMBMkx86OeKAsfk3i8ZA8QAEe41SWb4r6Spo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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