SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc9e8b37cd8d8e99d07c7d5f5b42000523258503511466d4054564d94e7b21c9' 
  AND token = 'xy6ZuyFWOcHXl07l5nLtH+xqHCt+VrCYgg0j2khPY+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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