SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52cdd367126438d527561606c5e9c6028a72f149ea01ff9def825a17e111d290' 
  AND token = '6mZaANGUVkJ/5rvWeiEGSl/Rnu5koTa+7orxkLOVyFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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