SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '251b81eba7d4704b9ce2329b74b6288ae93aa42ce7003af3903bb72c10bb33b7' 
  AND token = 'lrVzBx41+gtfmqrfKXv0JgRDhPBWMto7XZBoZxh/Jxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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