SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c8443ce39dd4c5b67a6fe7f9b6cda6bf01e35a27e81c850d51678063e9f35f' 
  AND token = '6Nlj2VMp6C/ZTFivEomxCjSL1hjVGoJM5Ikk59ugLAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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