SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '343afca78dc91fabdb45d5b3774de49b16c0c5e34ba5254b757ff1aa13c2b722' 
  AND token = '++nXVf/0iCq94tRePkVrLhFkOSpE8AfXgsetkiz3Lek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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