SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3470f53d832c0728774049fede475f9b4725f80c52d06a58dedf7332ad2c0387' 
  AND token = '18darRbwsU+xJHUtLy4zuaUg83lbuFsQ18ytQ73a4Wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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