SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3171f43896a45a7ed4ca25ce5939ede01afd4b682c93ca0acce1b11ed54f94e' 
  AND token = 'UvusTVE5tcxiznQVIURUZCAscvQE0fSck/gJAHT6L4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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