SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a6a2326fd2f8226612159f4c4ba07a28181fceb43b983e757e89283835bc03ac' 
  AND token = 'kd7FWJf9PnSG8v4hF1Z+YCGYImjXVewYbeiZL11ot/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}