SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4957d39f5b63ac3580ac15c246a98e46c1e170c2543e1bb099dd8a8662021ed' 
  AND token = 'Gr0eh0V7AOzyTqfLOoxJAhoklLPkx/4D94+qOEMdLz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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