SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6343d22ad3ee1b1bf3cbbee583241b4190b5630c5a43b7d70384ad812344f3c' 
  AND token = 'rJrLHGcRlHTIwjzCvixTZGs9QS59E4ACZcDe/EvAfYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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