SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c08b1520ad2740e2d89101aedadaed13ef937520fdf8c9d8efba8c708a569f6' 
  AND token = 'MbHvdF4u0xHCHglxnozDAh5+jzT/KxXlvtfLChQX4Ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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