SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '781f5f5b4241557499f6eda5a0da908d295b9e760fd1ee700de8b018ad7efcd0' 
  AND token = '1qp0Fo+ijd83PBucyMzE1caqWnrikyMnVcieCjDlk8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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