SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9951cee11d0da11bf3670737e5d006b51b4b309ecd0be06c75ac19b84865ced7' 
  AND token = 'dX+0VrO940VhRcu6xGiQB/hRQKarv6WcjXAgEwtGCDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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