SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '706b49dce84c1209e05408a87d3a13e711fede7ae27f19c6538e125232a1d76f' 
  AND token = 'lwqfyQDe7Zkx8gmJhtRJrBNzvJXwwpXaAPUzwzpJPuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}