SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7df265af7055b47adebb6583d5c5f1797721e7f3470fdd9672935a3a125d42a' 
  AND token = 'kGpyBOClN8CtJsSNrgWa7iyZp/FozVAUarOHrx82yHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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