SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c8a10189541c68da1a1092e57b0ea2b6fbad2cda85a53fdc5efe1e42f2a4c19' 
  AND token = 'VCGFdZ//0hPvmJgh9BDbNM/VViGmYZuXiF6qCqf66yc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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