SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30f36d575d88a68d60b6d9aed4ca2a08107637651ffd5f811070f8b84b566e9b' 
  AND token = 'BZqple2YS6MQMpkzPbPyWaHaime4cJaImZJft9qYkQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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