SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '762fc0fcfbb5014460286af1cd87805bbbb4e2a13721acb08453ca7f7b008544' 
  AND token = 'KYgGkSJeRg/U2sw6TmkmwH2IVkEhpuYQoJrhb/Z/nMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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