SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd8f54575b88948455e962385e93910620cc51e29a2ad9adce4f8f453de76956' 
  AND token = 'xLVlcSLZWRJwyzYuKu80dk9DwesrMMXNm+d2qFTh3dQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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